Enameling metal



Men M Patented Mar. 30, 1926.

UNITED STATES sassin Q a 1,578,706

PATENT OFFICE.

WESLEY J. BECK AND JAMES A. AUPPERLE, OF MIDDLE'IOIFN, OHIO, ASSIGN ORS TO THE AMERICAN ROLLING .MILLOOMPANY, OF MIDDLETOWN, OHIO, A CORPORA- TION OF OHIO.

No Drawing.

To allwhom it may concern;

Be it known that we, WESLEY J. BECK and JAMES A. AUPPERLE, citizens of the United States, and residents of Middletowmin the county of Butler and State of Ohio, have an enameling stock in the arts, there has been much difliculty, chiefly because of the 'fact' that in the enameling processwhere the enamel is baked onto the metal, the

gaseous constituent of the metal would form largegand small spots or uneven places beneath the enamel which destroyed the high quality appearance required in most products.

The production of a material in which part of a heat is good for enameling and part not good, is possible but as can readily be seen, the defect is the numerous sheets forming relatively bad parts of the heat, could not be discovered until the same were in the hands of the customer, whereupon the defect would cause him loss in some of the material delivered to him. Thus it is necessary to produce the metal so that in all parts of the heat, as finished into sheets, the quality will be uniform, as well as being as near perfect as possible.

In order to provide a material for enameling, it has been the effort for many years to provide a commercially pure iron, but it has been found that there are very severe limits within which anenameling material can be produced by this method.

After some years of experimentation, however, and a full test of the material in practice, extending over enough time to fully warrant the conclusions and practices outlined below, we have arrived at the analyses, proportions and temperatures conditions, which will result in a uniform, almost perfectly conditioned sheet for enameling, particularly when made in the open hearth fur-. nace. Among other things it is our object to obtain an iron of the greatest uniformity, which has a'definiteoxide constituent. This oxide according to .our theory, unites with the enamel in the baking process with the result of very firm anchorage or adherence I EnmELmq METAL.

Application-filed November 16, 1923. Serial No. 675,207.

thereof. Also the free or liberatablegas constituent in our material is so low that no bubbles or spots will develop in the heat treated, pickled and baked enameledsheet.

We produce the novel material by that certain process, and regulation of steps in- .the production ofthe material to be hereinafter more specifically pointed, out and claimed. v lfor example in the case of the open hearth process, we proceed as in mild steel practice,

but vary this process by keeping up the temperatures, and continuing to ore down, until a high degree of refinement. of the charge has'been obtained. Thus instead of decreasing the temperatures, we tend to increase, rather than to decrease toward the end of the melt in the furnace.

In the first place we find that any highly refined substantially carbonless and manganeseless iron, which develops a skull in the ladle, isnot a proper material for enameling stock, and without expressing the temperature in degrees we give the above. as a guide. to the necessary temperatures to be given to the material in the furnace and in the ladle.

Naturally the temperatures will have to be I high because a pure 1r0n of the character in question will develop a skull at a much higher temperature than mild steel.

In the next place we have found that if the manganese content is more than approximately .04 percent of the metal upon tapping, that the condition of the metal after degasification and deoxidization is not sufficiently uniforpn for the best enameling material. I

In fact the manganese content, which is chemically determined in the bath test, should be below .04 per cent, and preferably below .025 percent. This gives us two very important factors. In the first place'with. such a low manganese content, we find by means of the microscope, throughout the finished sheet, ready for enameling, a peculiar condition of oxide of iron, which gives the best obtainable fusion with vitreous enamel of any sheet metal with which we are familiar. In the next place, we find that the product is so regular within this manganese range where ordinary care is used in selection of raw materials, particularly the scrap, that definite proportions of aluminum can be used as a degasifier and deoxidizer, giving a sound ingot, practically free from blow holes, and having the oxide inclusions to which we have referred. 1

For instance, as the manganese decreases below .04 percent, the amount of aluminum or other deoxidi'zer mustbe increased, and by bath test determination of the manganesecontent, the man skilled in the art can determine by experiment the amount of alu-- minum or other deoxidizer to be added to the ladle to. produce ingots which have rimmed to the proper extent for iron to be used for vitreous enameling. Too much pipe is bad from the point of view of economy. By rimmed we mean that the ingots have at the top' a rim within which is a depression or cup. This cup or external pipe should be present in proper ingots but should not be more than say six inches deep, for example, in an 18 x 20 mold.

' We do not here specify certain proportions of aluminum, as the skilled producer should determine this for himself, based uponthe oxide inclusions and manganese content of the metal.

The aluminum used may not be the same as available to us at this time, the size of the ingots, and the-rapidity of action of his furnace may not correspond to ours, so that a separate determination, using the guides given will result in the best practice.

The properly prepared sheet will show 'a large number of spots of oxide inclusions I well distributed in the metal visible with a microscope. 4

Having thus described our invention, what weclaim as new and desire to secure by Letters Patent, is: r

1, An article used for receiving a coating of enamel in the presence of heat, formed of open hearth or similar ingot iron refined to a stage where the manganese content is below 04% and degasification has taken place to the extent of leaving a substantially sound metal, and not to the extent of eliminating all the oxide content, the said iron exhibiting under the microscope numerous well distributed spots of oxide in the surface and through the body thereof.

2; An article used for'receiving a coating of vitreous enamel formed mainly of iron, degasified to the extent of freeing the body of gas content thereby avoiding formation of spots and blisters while enameling, but

insufliciently deoxidized to eliminate oxide, said oxide appearing in substantial inclusions visible with the microscope on the surface and through the body of the iron in numerous, well distributed spots.

3. An articleused for receiving a coating of enamel in the presence of heat, formed of open hearth or ingot iron refined to a stage Where the manganese content is below 04% and degasification has taken place to the extent of leaving a substantially sound metal, and not to the extent of eliminating all the oxide content, the said iron exhibiting under the microscope numerous well dis tributed spots of oxide in the surface thereof, said iron having been removed from the open hearth furnace at a temperature sufliciently high to maintain the contents of the ladle liquid during the pouring into the ingot molds.

' WESLEY J. BECK.

JAMES- A. AUBPERLE. 

